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• Features utilized in cladistic analysis should be genetically determined and heritable, relatively invariable within an OTU, and denote clear discontinuities from other similar characters
• A single morphological feature may be the product of several inter-coordinated genes
• Defining a feature in terms of characters and character states can be problematic as a structure may have several components
• Characters are correlated when there is an interaction between what are defined as separate characters, but which are actually components of a common structure
• If two characters are correlated, they can be combined into one character or committed to character weighting
• Weighting means giving each character its degree of importance in the analysis
• Homology refers to similarity resulting from common ancestry, while homoplasy is similarity seen in individuals that do not share common ancestry
• Homoplasy can arise through convergence (independent evolution of a similar feature in two or more lineages) and reversal (loss of a derived feature with the re-establishment of an ancestral feature)
• Transformation series or morphocline is the arrangement of character states of each character in a sequence
• Binary characters have only two character states, while multi-state characters have three or more character states
• Ordered transformation series places character states in a predetermined sequence that may be linear or branched
• Character weighting involves assigning greater or lesser taxonomic importance to certain characters in determining phylogenetic relationships
• Characters with greater degrees of homology are given more weight as evidence of common ancestry
• If there are four correlated characters, each character will be given a weight of 1⁄4
• Polarity involves designating relative ancestry to the character states of a morphocline
• Primary procedure for determining polarity is outgroup comparison
• Before constructing a cladogram, characters and character states for each taxon are tabulated in a character x taxon matrix
• Recency of common ancestry is essential in cladistic analysis to assess descent
• Monophyletic group consists of a common ancestor plus all descendants of that ancestor
• Polyphyly is a form of non-monophyly
• Parsimony analysis involves choosing the cladogram with the least number of evolutionary changes
• Ockham's razor principle states that the simplest hypothesis is accepted when multiple hypotheses can explain the facts
• Following the principle of parsimony minimizes the number of homoplasious reversals or convergences
• Unrooted trees are constructed by grouping taxa without indicating polarity or ancestry
• Using a network cannot imply evolutionary relationships, show absence of a common ancestor, or recognize monophyletic groups